DESCRIPTION

Adult - This black, shield-shaped bug is brightly colored with orange, red, and yellow
markings. It varies from 7 to 10 mm in length.

Egg - The barrel-shaped egg, about 1 mm long, is light gray or pale yellow. It has two
black bands -- one at the top, the other near the bottom -- and a black spot just above the lower
band. Eggs are laid in clusters on crucifer foliage.

Nymph - The oval nymph is similar to the adult in coloration, but is slightly smaller and
lacks wings.

BIOLOGY

Distribution - Native to Central America and Mexico, the harlequin bug is now found
from coast to coast in North America as far north as the Great Lakes and New England. It is most
injurious, however, in the southern states and rarely causes damage north of latitude 40 N.

Host Plants - Harlequin bugs attack nearly all crucifers, including common weeds of the
mustard family such as wild mustard, shepherdspurse, peppergrass, bittercress, and watercress. If
infestations are heavy and food becomes scarce, harlequin bugs will also feed on squash, corn,
bean, asparagus, okra, and tomato.

Damage - Adults and nymphs pierce stalks, leaves, and veins with their needle-like
mouthparts and extract plant juices. Stems and leaves injured in this manner develop irregular
cloudy spots around the puncture wound. Young plants are likely to wilt, turn brown, and
eventually die; while older plants are only stunted.

Life History - Harlequin bugs overwinter as adults throughout most of their range. They
remain active throughout the mild winters of the Gulf States, but hibernate among plant debris
during the harsh winters of northern states. Adults emerge early in spring. Approximately 2 weeks
after resuming activity, females begin depositing eggs on the undersides of leaves. Eggs are laid in
double-row clusters of 10 to 13 until each female has deposited approximately 155 eggs. In early
spring, eggs hatch in about 20 days. Eggs hatch in 4 to 5 days as the weather becomes warmer.
Nymphs feed for 6 to 8 weeks and develop through 5 instars before becoming adults. Two to 4
generations occur each year in North Carolina.

CONTROL

Populations of overwintering adults can be reduced by plowing under field debris after the onset
of cold weather. Destruction of weeds within fields and along fence rows also limits
overwintering sites. In addition to cultural practices, resistant varieties should be planted when
possible. The following varieties are recommended: Copenhagen Market 86, Headstart, Savoy
Perfection Drumhead, Stein's Flat Dutch, and Early Jersey Wakefield (cabbage); Green Glaze
(collards); Early Snowball X and Snowball Y (cauliflower); Red Devil, White Icicle, Globemaster,
Cherry Belle, Champion, and Red Prince (radish).

For chemical control of harlequin bug infestations, insecticides should be applied when bugs first
appear and applications repeated as necessary. For recommended insecticides and rates, consult
the current North Carolina Agricultural Chemicals Manual.